cool very informative. I have just set up a 180 gallon tank abt 2 weeks ago, planted some plants and most of them are growing well. Its a 6 foot long tank, and i am using 2 flouro tubes( Power -glo) 40 watt - 4 foot long tubes and i find that it gives enough light. My fish are happier, they seem to be behaving more naturally the more the plants grow. Although the tank is still cloudy due to the "cycle" which is still not complete. I am hoping to a few more plants laters stages to enchance the tank.